Drying cylinder assembly

ABSTRACT

A drying cylinder assembly for drying of a web material. The assembly comprises a rotating cylinder and at least one dipper pipe fastened inside the cylinder to rotate therewith. The dipper pipe is provided with dipper straws. The apertures of the dipper pipes are positioned on a line which deviates from the direction of the cylinder axis.

United States Patent [191 Ebeling [451 Apr. 9, 1974 DRYING CYLINDER ASSEMBLY [75] Inventor: Kari Ebeling, Koskenmaki, Finland [73] Assignee: 0y Nokia Ab, Helsinki, Finland [22] Filed: June 28, 1972 [21] Appl. N0.: 267,047

[30] Foreign Application Priority Data June 29, 1971 Finland 1826/71 [52] U.S. Cl. 34/124, 165/91 [51] Int. Cl. F26b 11/02 [58] Field of Search 34/119, 124, 125; 165/89-91 [56] References Cited UNITED STATES PATENTS 3,481,050 12/1969 Cox, Jr. 34/124 3,241,251 3/1966 Justus et a1. 34/124 Primary Examiner-John J. Camlby Assistant Examiner-James C. Yeung Attorney, Agent, or Firm-Eric H1. Waters [5 7] ABSTRACT A drying cylinder assembly for drying of a web material. The assembly comprises a rotating cylinder and at least one dipper pipe fastened inside the cylinder to rotate therewith. The dipper pipe is provided with dipper straws. The apertures of the dipper pipes are positioned on a line which deviates from the direction of the cylinder axis.

5 Claims, 4 Drawing Figures PMENTEDAPR 9 m4 3.802.093

SHEET 2 [1F 2 DRYING CYLINDER ASSEMBLY The present invention relates to a drying cylinder assembly comprising a cylinder rotating about a horizontal axle, a dipper pipe, located inside and attached to the cylinder to rotate therewith and dipper straws, for condensed steam, fitted on the dipper pipe and extending substantially to the inner surface of the cylinder.

This invention is especially suitable for Yankee cylinders of high speed crepe paper machines.

In a drying cylinder assembly of previously known type, the drying cylinder is equipped with dipper pipes which extend parallel to the axis of the cylinder and to which clipper pipes dipper straws are attached. These dipper straws extend substantially to the cylindrical inner surface of the cylinder in order to remove condensed steam collected on this surface, the said condensed steam originating from the steam which is directed into the cylinder to heat it.

It has been observed that in a high speed crepe paper machine equipped with this type of drying cylinder socalled wave marks appear on the outer surface of the drying cylinder when a paper web dried with this type of cylinder is removed from the outer surface of the drying cylinder by means of a doctor blade.

Such wave marks appear along a line corresponding to the line through the dipper straw apertures on the outer surface of the cylinder in previously known drying cylinder assemblies. This is because the paper web adheres more firmly to the outer surface of the cylinder over a narrow surface strip corresponding to said line through the apertures, since, owing to the removal of condensed steam, there is along said surface strip a temperature difference compared with adjacent areas of the surface. As the dipper pipe in known drying cylinders is dispolsed longitudinally within the same or, in other words, is parallel to the corresponding cylinder axis, the line through the dipper straw apertures is also parallel to the cylinder axis and the said surface strip on the cylinder along which the paper web adheres more firmly is also parallell to the cylinder axis. Because of this, the doctor blade, the edge of which is in contact with the outer surface of the cylinder and, for practical reasons, is parallel to the cylinder axis, has a more difficult loosening operation to carry out along the whole of its length when it encounters the said surface strip. Owing to this unevenness in the loosening operation the edge of the doctor blade tends to hit against the surface of the cylinder as the said surface strip passes the blade during rotation of the cylinder.

An objects of this invention is to prevent the appearance of wave marks on the outer surface of the cylinder, and this is achieved by means of a drying cylinder assembly characterized in that the dipper pipe is mounted in the cylinder in such a way that a line through the dipper straw aperture openings deviates from or forms an angle with the direction of the cylinder axis.

Since the line through the dipper straw aperture openings is not parallel to the cylinder axis in a drying cylinder assembly in accordance with the invention, neither is the surface strip to which the paper web adheres more firmly on the outer surface parallel to the cylinder axis. For this reason, only a small portion of the edge of the doctor blade encounters, at any one time, that part of the surface strip along which the paper adheres more firmly to the outer surface of the cylinder. The more difficult loosening work along said surface strip can then be performed gradually and by different parts of the edge of the doctor blade. This results in a more even strain along the blade edge which eliminates both the hitting of said edge against the cylinder surface and the appearance of wave marks on the outer surface of the cylinder.

The invention is described in more detail in the following, with reference to the appended drawings, in which:

FIG. 1 is a perspective view partly in section of a first embodiment of a drying cylinder assembly in accordance with the invention comprising a straight dipper FIG. 2 is a similar view of a second embodiment comprising a curved dipper pipe;

FIG. 3 is a similar view of a third embodiment comprising a doubly curved dipper pipe; and

FIG. 4 is an axial cross-sectional view on a larger scale of a portion of the cylinder wall and dipper straws.

The drying cylinder assembly shown in FIG. 1 comprises a hollow drying cylinder 1 of circular crosssection on which a paper web 2 is dried. The drying cylinder shown is of the type in which the cylinder wall is provided with several reinforcement ribs 3 extending all around the inner surface of the cylinder and mutually spaced to form ring shaped grooves 4. For the sake of clarity these grooves on the inner surface of the cylinder are not completely shown in FIG. 1, but they can be seen in detail in FIG. 4.

A doctor blade 5, the sharp edge 6 of which is pressed against the outer surface of the cylinder to remove the paper web 2 from the cylinder, is located out side the cylinder 1. The edge 6 of the doctor blade is parallel to the axis Aof the cylinder.

The drying cylinder 1 is fitted with end plates 7 at each end to which a hollow shaft Shaving projecting ends 9 and 10 is centrally fixed. One or more dipper pipes 11, for the collection of condensed steam, are fitted inside the cylinder near its inner surface and attached to the axle 8 so that they rotate with the cylinder. The dipper pipe has closed ends and is joined to the shaft 8 by means of a connector tube 12. Several dipper straws 13 are fitted to the pipe 11 in such a way that their apertures 14are positioned quite near to the bottoms of the grooves 4 on the inner surface of the cylinder, as shown in detail in FIG. 4. In order to obtain a more even heat transfer, it is preferable that the dipper straws 13 of each dipper pipes 11 do not occupy every groove 4, but the dipper straws of the various pipes should be located in such a way that every groove 4 is occupied by at least one dipper straw 13.

In this embodiment the dipper pipe 11 is straight, and has been located in the cylinder 1 at an angle to the cylinder axis A, so that the line B through the dipper straw apertures 14 also forms an angle with the said axis. The lengths of the straws 13 are adjusted so that their apertures are each located at the same distance from the inner surface of the cylinder, or the bottoms of the grooves, in spite of the oblique position of the dipper pipe.

Steam is supplied into the cylinder in a conventional manner for heating purposes through one shaft end 10, into the hollow shaft 8, and then outthrough the diffusion pipes 15 fixed to the shaft. The condensedsteam is collected from the bottoms of the grooves into two dipper pipes 11 in a conventional manner, while the unsaturated steam flows in through the apertures 14. The condensed steam is passed from the dipper pipe via the connector pipe 12 into the shaft 8 and out therefrom through the other shaft end 9. An intermediate wall, perpendicular to the shaft, divides the shaft into two compartments so that steam entering through the shaft end cannot pass straight out through the shaft end 9, but is forced to first circulate inside the cylinder.

From FIG. 1 appears that the edge 6 of the doctor blade makes an angle with the line B through the dipper straw apertures, and it does not therefore pass at the same time with its whole length the line through the dipper straw apertures when the cylinder is in rotation, but does it gradually with different portions of the edge.

The arrangement shown in FIG. 2 differs from that shown in FIG. 1 only in the respect that the dipper pipe 16 is curved in such a way that it is equidistant from the inner surface of the cylinder 1 over its whole length, in spite of being located at an angle to the axis A. All the dipper straws 17 are of equal length.

The embodiment shown in FIG. 3 differs from the previous two in the respect that the dipper pipe 18 is made up of two curved sections of pipe joined together at the middle of the cylinder. Also in this case the pipes are curved in such a way as to follow the inner surface of cylinder 1, as in FIG. 2. The dipper straws 19 are thus of equal length. The line B through the dipper straw apertures again forms an angle with the axis A.

The figures and their associated descriptions are only intended to give a broad outline of the idea of the invention. The details of an embodiment in accordance with the invention can vary considerably within the appended claims. The dipper pipe according to FIG. 2 may, for example, be curved in one plane only or curved in two different planes.

What I claim is:

1. A drying cylinder assembly comprising an at least substantially horizontal axle, a cylinder having an inner surface and rotating on and about said horizontal axle and defining an axis of rotation, means to feed steam into the cylinder to heat the same, at least part of said steam condensing within the cylinder, at least one dipper pipe located inside and attached to the cylinder to rotate with the cylinder, and dipper straws on said dipper pipe for removal of the condensed steam in the cylinder, said dipper straws extending substantially to the inner surface of the cylinder, the dipper straws being provided with aperture openings, said openings of the dipper straws being arranged on a common line forming a transverse angle with the cylinder axis.

2. An assembly according to claim 1, wherein the dipper pipe is straight and is fitted inside the cylinder at an angle to the axis, the dipper straws being attached to said pipe along a line parallel to the pipe.

3. An assembly according to claim 1, wherein the dipper pipe is curved and is fitted inside the cylinder at an angle to the axis and follows the curve of the inner surface of the cylinder, the dipper straws being attached to said pipe along a line parallel to the pipe.

4. An assembly according to claim 1, wherein the dipper pipe includes at least two curved pipe sections and is fitted inside the cylinder with each pipe section positioned at an angle to the cylinder axis to follow substantially the curve of the inner surface of the cylinder, the dipper straws being attached to said pipe sections in lines parallel to the pipe sections.

5. An assembly according to claim 1 wherein said common line does not lie in a common plane with the cylinder axis. 

1. A drying cylinder assembly comprising an at least substantially horizontal axle, a cylinder having an inner surface and rotating on and about said horizontal axle and defining an axis of rotation, means to feed steam into the cylinder to heat the same, at least part of said steam condensing within the cylinder, at least one dipper pipe located inside and attached to the cylinder to rotate with the cylinder, and dipper straws on said dipper pipe for removal of the condensed steam in the cylinder, said dipper straws extending substantially to the inner surface of the cylinder, the dipper straws being provided with aperture openings, said openings of the dipper straws being arranged on a common line forming a transverse angle with the cylinder axis.
 2. An assembly according to claim 1, wherein the dipper pipe is straight and is fitted inside the cylinder at an angle to the axis, the dipper straws being attached to said pipe along a line parallel to the pipe.
 3. An assembly according to claim 1, wherein the dipper pipe is curved and is fitted inside the cylinder at an angle to the axis and follows the curve of the inner surface of the cylinder, the dipper straws being attached to said pipe along a line parallel to the pipe.
 4. An assembly according to claim 1, wherein the dipper pipe includes at least two curved pipe sections and is fitted inside the cylinder with each pipe section positioned at an angle to the cylinder axis to follow substantially the curve of the inner surface of the cylinder, the dipper straws being attached to said pipe sections in lines parallel to the pipe sections.
 5. An assembly according to claim 1 wherein said common line does not lie in a common plane with the cylinder axis. 